Conserved Protein Domain Family
C2B_Synaptotagmin-13

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cd08407: C2B_Synaptotagmin-13 
C2 domain second repeat present in Synaptotagmin 13
Synaptotagmin is a membrane-trafficking protein characterized by a N-terminal transmembrane region, a linker, and 2 C-terminal C2 domains. Synaptotagmin 13, a member of class 6 synaptotagmins, is located in the brain. It functions are unknown. It, like synaptotagmins 8 and 12, does not have any consensus Ca2+ binding sites. Previously all synaptotagmins were thought to be calcium sensors in the regulation of neurotransmitter release and hormone secretion, but it has been shown that not all of them bind calcium. Of the 17 identified synaptotagmins only 8 bind calcium (1-3, 5-7, 9, 10). The function of the two C2 domains that bind calcium are: regulating the fusion step of synaptic vesicle exocytosis (C2A) and binding to phosphatidyl-inositol-3,4,5-triphosphate (PIP3) in the absence of calcium ions and to phosphatidylinositol bisphosphate (PIP2) in their presence (C2B). C2B also regulates also the recycling step of synaptic vesicles. C2 domains fold into an 8-standed beta-sandwich that can adopt 2 structural arrangements: Type I and Type II, distinguished by a circular permutation involving their N- and C-terminal beta strands. Many C2 domains are Ca2+-dependent membrane-targeting modules that bind a wide variety of substances including bind phospholipids, inositol polyphosphates, and intracellular proteins. Most C2 domain proteins are either signal transduction enzymes that contain a single C2 domain, such as protein kinase C, or membrane trafficking proteins which contain at least two C2 domains, such as synaptotagmin 1. However, there are a few exceptions to this including RIM isoforms and some splice variants of piccolo/aczonin and intersectin which only have a single C2 domain. C2 domains with a calcium binding region have negatively charged residues, primarily aspartates, that serve as ligands for calcium ions. This cd contains the second C2 repeat, C2B, and has a type-I topology.
Statistics
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PSSM-Id: 176052
View PSSM: cd08407
Aligned: 3 rows
Threshold Bit Score: 256.831
Threshold Setting Gi: 62955281
Created: 22-Sep-2009
Updated: 2-Oct-2020
Structure
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Aligned Rows:
PubMed ReferencesClick to see Conserved Features Help

Sequence Alignment
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Format: Row Display: Color Bits: Type Selection:
Q7L8C5       288 AGEVLLSISYLPAaNRLLVVLIKAKNLHsnqskellGKDVSVKVTLKHqarKLKKKQTKRAKHKINPVWNEMIMFELPdd 367 human
NP_001017652 284 TGELLLSLSYLPAaNRLGVVVMKARGLQsdk--lkdNIDLSVKLTLKHqnaKLKKKQTRRVKHKMNPVWNEMMMLELPse 361 zebrafish
XP_421100    290 HGEVLLSISYLPAaNRLLVVIIKAKNLHskqlkdllGNDVSVKVTLRHqslKLKKKQTKHAKHKINPVWNEMIMFEVPhe 369 chicken
Q7L8C5       368 llqasSVELEVLGQDDsgQSCALGHCSLGLhtsgsERSHWEEMLKNprRQIAMWHQLH 425 human
NP_001017652 362 llaksSVDLEVLNLASpgTLLPLGRCMLGLqtsgtGLQHWKQMLDNprKQIAMWHPLY 419 zebrafish
XP_421100    370 llrasSVELEMLSQDGagQSQVLGKCSLGLhvtgtERNHWEEMLRNprRQIAMWHQLH 427 chicken
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